Apparatus for Molding Hairpin and Method of Inserting Hairpin Using the Same

ABSTRACT

An apparatus for molding a hairpin inserted into a stator core includes a clamping unit including a connection bracket mounted on a front end of a robot arm and at least one clamper mounted on the connection bracket and configured to be reciprocally driven in opposite directions in a straight line, and a mold unit detachably coupled with the at least one clamper and configured to press mold a head portion of the hairpin by a molding jig configured to be driven by the at least one clamper.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Korean Patent Application No.10-2020-0077599, filed in the Korean Intellectual Property Office onJun. 25, 2020, which application is hereby incorporated herein byreference.

TECHNICAL FIELD

The present invention relates to an apparatus for molding a hairpin anda method of inserting a hairpin using the same.

BACKGROUND

Recently, a method for improving the output of a motor has been activelyresearched and developed to improve performance of electric vehicles.

In general, the output of the motor is known to be proportional to thenumber of turns of a stator coil wound on a stator core.

Accordingly, in order to improve the output without increasing the sizeof the motor, a method of increasing the space factor of the stator coilwound on the stator core may be considered.

As part of the above-described method, instead of using a circular coilhaving a circular cross-section, a method of winding using a flat coilhaving a square cross-section has been researched.

However, in the case of flat coils, there are relative difficulties inwinding coils compared to circular coils.

Therefore, as a method of facilitating winding in a flat coil, a type ofmotor (hereinafter called a hairpin winding motor) has been proposed, inwhich a plurality of separated hairpin type stator coils (hereinafterreferred to as hairpins) are inserted into the stator core, and thenrespective hairpins are welded to form a coil winding part.

In the hairpin winding motor as described above, U-shaped hairpins areinserted into each slot of the stator core, and then the hairpinsdisposed in each layer of each slot are welded to form a coil winding ofthe stator core.

Here, the process of molding the hairpins may be classified into acomputerized numerical control (CNC) molding method and a press moldingmethod. Since there are several types of hairpins in one hairpin drivemotor, the CNC molding method capable of handling various types ofhairpins is advantageous.

However, the CNC molding method capable of handling various types ofhairpins according to conventional art consumes about six seconds forthe production speed of one hairpin, so the production speed is slightlyslow. In contrast, the press molding method with faster speed generallytakes about three seconds for each hairpin, having twice theproductivity compared to the CNC molding method, but there is a drawbackof handling only a single type of hairpins.

Therefore, it may be advantageous to research and develop a methodproviding capability of molding plural types of hairpins and insertingthe hairpins into the stator coil.

The above information disclosed in this Background section is only forenhancement of understanding of the background of the invention, andtherefore it may contain information that does not form the prior artthat is already known to a person of ordinary skill in the art.

SUMMARY

An apparatus for molding a hairpin inserted into a stator core includesa clamping unit including a connection bracket mounted on a front end ofa robot arm and at least one clamper mounted on the connection bracketand reciprocally driven in opposite directions in a straight line, and amold unit detachably coupled with the at least one clamper and pressmolding a head portion of the hairpin by a molding jig driven by the atleast one clamper.

The at least one clamper may include a pair of clampers, each of whichmay include a first end mounted on the connection bracket and a secondend on which a fitting end protrudes. The pair of clampers mayreciprocate to become closer and farther with reference to a centralportion of the connection bracket.

The fitting end may be slidably inserted into a mounting slot formed inthe molding jig.

The mold unit may be detachably coupled with the connection bracket at aposition between the at least one clamper, by a fixing chuck.

The fixing chuck may include a fixing block mounted on the connectionbracket, and a plurality of fixing pins disposed along an exteriorcircumference of the fixing block, and operable to be inserted into thefixing block and to protrude on the fixing block 33.

The mold unit may include a fixing plate coupled to the connectionbracket through the fixing chuck, a support bar fixed to the fixingplate, and at least one molding jig coupled with the at least oneclamper and driven by the at least one clamper to move along the supportbar to mold a head portion of the hairpin.

The at least one molding jig may include a first jig and a second jigcoupled with the at least one clamper. The first jig and the second jigmay be moved to be closer or farther along a guide bar.

A method of inserting a hairpin into a stator core may include unwindinga coil spiral-wound on an uncoiler, forming a decoated portion bydecoating a predetermined portion on the coil by a heating device,bending the coil in multiple stages to two-dimensionally form a legportion and a head portion by a bending device, cutting the coil formedwith the leg portion and the head portion by a predetermined length by acutting device, and moving the hairpin to be inserted into the statorcore while three-dimensionally forming the head portion, by a samemolding apparatus.

The bending of the coil in multiple stages may be performed by acomputerized numerical control bending device.

The bending of the coil in multiple stages may be performed by a pressbending device.

The moving of the hairpin to be inserted into the stator core whilethree-dimensionally forming the head portion includes coupling a fixingblock to a fixing chuck of a connection bracket while a molding jig isinserted into at least one clamper, loading the coil such that the headportion that has been two-dimensionally formed by the bending device isinterposed between the molding jigs, three-dimensionally forming thehead portion while the molding jigs are brought tightly close togetherby the at least one clamper, and moving the hair pin whilethree-dimensionally forming the head portion by the same moldingapparatus.

The moving of the hairpin to be inserted into the stator core whilethree-dimensionally forming the head portion may further includealigning the hairpin into a dummy core while forming the hairpin byusing the same molding apparatus and inserting the hairpins aligned inthe dummy core into slots of the stator core by an extracting gripperunit.

According to an apparatus for molding hairpins and a method of insertinga hairpin using the same according to an exemplary embodiment, moldingthe hairpins and inserting the molded hairpins may be simultaneouslyperformed by using the molding apparatus, thereby improving productivityby reducing an overall cycle time.

In addition, according to an apparatus for molding hairpins and a methodof inserting a hairpin using the same according to an exemplaryembodiment, a loading space for loading molded hairpins and a carrier ormoving system for the loaded hairpins may be removed, thereby minimizinga work space and reducing investment cost.

Other effects that may be obtained or are predicted by exemplaryembodiments will be explicitly or implicitly described in a detaileddescription of embodiments of the present invention. That is, variouseffects that are predicted according to exemplary embodiments will bedescribed in the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically illustrates a structure of a hairpin winding typestator of a drive motor applied to an exemplary embodiment.

FIG. 2 is a perspective view of an apparatus for molding hairpinsaccording to an exemplary embodiment.

FIG. 3 illustrates an operation of an apparatus for molding hairpinsaccording to an exemplary embodiment.

FIG. 4 is a perspective view of an apparatus for molding hairpinsaccording to an exemplary embodiment.

FIG. 5, which includes FIGS. 5A and 5B, illustrates an operation of anapparatus for molding hairpins according to an exemplary embodiment.

FIG. 6 and FIG. 7 sequentially illustrate a method for insertinghairpins by using an apparatus for molding hairpins according to anexemplary embodiment.

The following reference numerals can be used in conjunction with thedrawings:

-   -   1: stator    -   3: stator core    -   5: slot    -   7: coil    -   9: dummy core    -   10: hairpin    -   11: head portion    -   13: leg portion    -   15: decoated portion    -   20: clamping unit    -   21: robot arm    -   23: connection bracket    -   25: clamper    -   27: driving portion    -   29: fitting end    -   30: fixing indentation    -   31: fixing chuck    -   33: fixing block    -   35: fixing pin    -   40: mold unit    -   41: fixing plate    -   43: mounting hole    -   45: support bar    -   47: guide bar    -   50: molding jig    -   51: first jig    -   53: second jig    -   55: mounting slot    -   57: molding surface    -   60: uncoiler    -   70: heating device    -   80: bending device    -   90: cutting device    -   100: molding apparatus    -   110: extracting gripper unit

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Hereinafter, the present invention will be described more fullyhereinafter with reference to the accompanying drawings, in whichexemplary embodiments of the invention are shown. As those skilled inthe art would realize, the described embodiments may be modified invarious different ways, all without departing from the spirit or scopeof the present invention.

In order to clarify embodiments of the present invention, parts that arenot connected to the description will be omitted, and the same elementsor equivalents are referred to with the same reference numeralsthroughout the specification.

In the following description, dividing names of components into first,second, and the like is to divide the names because the names of thecomponents are the same as each other, and an order thereof is notparticularly limited.

FIG. 1 schematically illustrates a structure of a hairpin winding typestator of a drive motor applied to an exemplary embodiment.

Referring to FIG. 1, a hairpin winding type stator 1 of a drive motorapplied to an exemplary embodiment may be applied to a drive motor foran electric vehicle such as a hybrid electric vehicle that outputsdriving torque from electrical energy.

Such a drive motor includes a stator 1, a rotor (not shown) disposedwith a certain gap with the stator 1, and a plurality of permanentmagnets (not shown) installed on the rotor.

The stator 1 includes a stator core 3 formed as a stack of a pluralityof electrical steel sheets, and stator coils (hereinafter calledhairpins) 10 of a hairpin type are wound on the stator core 3 through aplurality of slots 5.

In addition, the rotor includes a rotor core formed as a stack of aplurality of electrical steel sheets in an axial direction, and thepermanent magnet is installed by being inserted in insertion holesprovided in the rotor core.

In addition, the hairpins 10 are flat coils, having a pair of legportions 13 on both sides of a head portion 11, and are generallyU-shaped or V-shaped. The hairpins 10 may be formed as flat coils of asquare cross-section.

The hairpins 10 are inserted into the predetermined layer (indicated bydotted lines in the drawing) of a slot 5 in the stator core 3. At thistime, decoated portions 15 formed at ends of the pair of leg portions 13protrudes exteriorly from the slot 5 to be exposed below a bottom of thestator core 3, and the decoated portions 15 are welded to form anelectrically connected coil winding.

Although it is described above that an exemplary embodiment of thepresent invention is applied to the stator 1 of a hairpin winding typefor a drive motor, the scope of the present invention is not necessarilylimited thereto. It may be understood that the technical disclosure ofan exemplary embodiment may be applied to a drive motor having thehairpins 10 of various types and uses.

FIG. 2 is a perspective view of an apparatus for molding hairpinsaccording to an exemplary embodiment. FIG. 3 illustrates an operation ofan apparatus for molding hairpins according to an exemplary embodiment.FIG. 4 is a perspective view of an apparatus for molding hairpinsaccording to an exemplary embodiment. FIG. 5, which includes FIGS. 5Aand 5B, illustrates an operation of an apparatus for molding hairpinsaccording to an exemplary embodiment.

An apparatus for molding hairpins and a method of inserting a hairpinusing the same according to an exemplary embodiment unwinds a coil 7spiral-wound on an uncoiler 60, molds the coil 7 into the hairpins 10each having the head portion 11, and then inserts the hairpins 10 intothe stator core 3, thereby achieving automation of an overall process.

For such a purpose, an apparatus 100 for molding hairpins according toan exemplary embodiment includes a clamping unit 20 and a mold unit 40.

Referring to FIG. 2, the clamping unit 20 is configured at a front endof a multi-axis robot arm 21.

The clamping unit 20 includes a connection bracket 23 mounted on thefront end of the robot arm 21.

A pair of clampers 25 is mounted on the connection bracket 23.

The pair of clampers 25 is reciprocally driven in opposite directions ina straight line.

That is, the pair of clampers 25 is formed in a lengthy rod shape, wherefirst ends of the clampers 25 are mounted on the connection bracket 23,and may reciprocate to become closer and farther with reference to acentral portion of the connection bracket 23.

At this time, a driving portion 27 driving the pair of clampers 25 maybe operated by a pneumatic cylinder.

Alternatively, the pair of clampers 25 may be operated by a drive motor.

The pair of clampers 25 respectively includes second ends facing eachother, and a fitting end 29 protrudes on each facing surface of thesecond ends.

The mold unit 40 is detachably fitted to the fitting end 29.

At this time, the mold unit 40 is detachably coupled with the connectionbracket 23 at a position between the pair of clampers 25, by a fixingchuck 31.

Referring to FIG. 3, the fixing chuck 31 includes a fixing block 33 anda fixing pin 35. The fixing block 33 is mounted on a fixing indentation30 of the connection bracket 23. A plurality of the fixing pins 35 maybe disposed along an exterior circumference of the fixing block 33, andmay operate to be inserted into the fixing block 33 (refer to thedrawing on the left in FIG. 3) and protrude from the fixing block 33(refer to the drawing on the right in FIG. 3).

The fixing fin 35 has a basic state of being inserted into the fixingblock 33, and for coupling to the mold unit 40, protrudes from thefixing block 33 to be coupled with a mounting hole 43 of the mold unit40.

The fixing pin 35 of the fixing chuck 31 may be pneumatically operated.

Meanwhile, referring to FIG. 4, the mold unit 40 fixed to the connectionbracket 23 through the fixing chuck 31 incudes a fixing plate 41, aplurality of support bars 45, and a pair of molding jigs 50.

In more detail, the mold unit 40 is coupled to the fixing chuck 31through the fixing plate 41.

The fixing plate 41 is formed with the mounting hole 43 for coupling tothe fixing chuck 31.

The mounting hole 43 is formed as a hole that may be coupled with thefixing block 33 and the fixing pin 35 installed on the fixing block 33.

In addition, the plurality of support bars 45 are fixed to the fixingplate 41 and the fixing plate 41 is mounted with the pair of moldingjigs 50 through the plurality of support bars 45.

The pair of molding jigs 50 includes a first jig 51 and a second jig 53.The first jig 51 and the second jig 53 are slidably coupled with thesupport bar 45, supported by a plurality of guide bars 47, andreciprocally driven in a straight line along the guide bars 47.

In addition, each of the first jig 51 and the second jig 53 is formedwith a mounting slot 55 into which the fitting end 29 of the pair ofclampers 25 may be slidably inserted.

That is, the mold unit 40 is mounted on the clamping unit 20 through thefixing chuck 31 while the fitting end 29 is inserted into the mountingslot 55.

Referring to FIGS. 5A and 5B, by the operation of the pair of clampers25, the first jig 51 and the second jig 53 in the mold unit 40 maybecome closer or farther and may be brought tightly close together toform the coil 7 therebetween.

At this time, the first jig 51 and the second jig 53 move along theguide bar 47.

Molding surfaces 57 of the first jig 51 and the second jig 53 are formedin shapes corresponding to a desired shape of the head portion 11 of thehairpins 10.

That is, according to an apparatus 100 for molding hairpins according toan exemplary embodiment, the mold unit 40 may be replaced from theclamping unit 20 according to a desired shape of the head portion 11 ofthe hairpins 10.

The hairpins 10 molded by using an apparatus 100 for molding hairpinsmay be inserted into the stator core 3 as follows.

FIG. 6 and FIG. 7 illustrate a sequential method for inserting hairpinsby using an apparatus for molding hairpins according to an exemplaryembodiment.

Referring to FIG. 6, according to an inserting method of hairpinsaccording to an exemplary embodiment of the present invention, thespiral-wound coil on the uncoiler 60 is unwound first.

At this time, the coil is coated with an insulating film of an enamelmaterial on a copper wire.

Subsequently, the coil is supplied to a heating device 70.

The heating device 70 is a device that heats the coil and peels off theinsulating film of the enamel material.

A predetermined portion of the coil is decoated by the heating device 70to form the decoated portion 15 on the coil.

Subsequently, the coil having the decoated portion 15 is supplied to abending device 80.

The bending device 80 forms a leg portion 13 and the head portion 11 inthe coil.

At this time, the bending device 80 may include a computerized numericalcontrol (CNC) bending device, or a press bending device.

The CNC bending device and the press bending device may be implementedas known in the art.

The bending device 80 is to bend the coil in multiple stages totwo-dimensionally form the leg portion 13 and the head portion 11.

The coil formed with the leg portion 13 and the head portion 11 is cutby a predetermined length by using a cutting device 90.

The hairpins 10 are formed in a shape having two leg portions 13 at bothsides of the head portion 11.

Here, the decoated portion 15 is formed at the distal end of each legportion 13 from the head portion 11.

The hairpins 10 may be welded at the decoated portions 15 after beinginserted into the stator core 3.

Subsequently, the head portion 11 is molded by the mold unit 40 of amolding apparatus 100.

In more detail, the mold unit 40 corresponding to a desired shape of thehead portion 11 is loaded on the clamping unit 20.

That is, while the molding jig 50 is inserted into the pair of clampers25, the fixing block 33 is coupled with the fixing chuck 31 of theconnection bracket 23.

The head portion 11 that has been two-dimensionally formed at thebending device 80 is interposed between the first jig 51 and the secondjig 53.

The first jig 51 and the second jig 53 are brought tightly closetogether by the pair of clampers 25, and thereby the head portion 11 isthree-dimensionally formed.

At this time, the molding apparatus 100 molds the hairpins 10 andsimultaneously, the molding apparatus 100 moves the molded hairpins 10to be inserted into the stator core while molding the hairpins 10.

For example, the molding apparatus 100 may mold the hairpins 10 andsimultaneously may insert the molded hairpins 10 into the slot 5 of thestator core 3.

Alternatively, referring to FIG. 7, the molding apparatus 100 may moldthe hairpins 10 and align the molded hairpins 10 into a dummy core 9 atthe same time, and then may simultaneously insert the hairpins 10aligned in the dummy core 9 into the stator core 3 by an extractinggripper unit 110.

Therefore, according to an apparatus for molding hairpins and a methodof inserting a hairpin using the same according to an exemplaryembodiment, molding the hairpins 10 and inserting the molded hairpinsmay be simultaneously performed by using the molding apparatus 100,thereby improving productivity by reducing an overall cycle time.

That is, according to an apparatus for molding a hairpin and a method ofinserting a hairpin using the same, full automation from molding of thehairpins 10 to inserting the molded hairpins into the stator core may beenabled.

In addition, according to an apparatus for molding hairpins and a methodof inserting a hairpin using the same according to an exemplaryembodiment, a loading space for loading molded hairpins and a carrier ormoving system for the loaded hairpins may be removed, thereby minimizinga work space and reducing investment cost.

In addition, according to an apparatus for molding hairpins and a methodof inserting a hairpin using the same according to an exemplaryembodiment, depending on a desired shape of the head portion 11 of thehairpins 10 to be molded, the mold unit 40 may be easily replaced in theclamping unit 20, thereby being capable of handling various types.

While this invention has been described in connection with what ispresently considered to be practical exemplary embodiments, it is to beunderstood that the invention is not limited to the disclosedembodiments. On the contrary, it is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims.

What is claimed is:
 1. An apparatus for molding a hairpin inserted intoa stator core, the apparatus comprising: a clamping unit including aconnection bracket mounted on a front end of a robot arm and at leastone clamper mounted on the connection bracket and configured to bereciprocally driven in opposite directions in a straight line; and amold unit detachably coupled with the at least one clamper andconfigured to press mold a head portion of the hairpin by a molding jigconfigured to be driven by the at least one clamper.
 2. The apparatus ofclaim 1, wherein: the at least one clamper comprises a pair of clampers,each of which comprises a first end mounted on the connection bracketand a second end on which a fitting end protrudes; and the pair ofclampers is configured to reciprocate to become closer and farther withreference to a central portion of the connection bracket.
 3. Theapparatus of claim 2, wherein the fitting end is slidably inserted intoa mounting slot formed in the molding jig.
 4. The apparatus of claim 2,wherein the mold unit is detachably coupled with the connection bracketat a position between the pair of clampers by a fixing chuck.
 5. Theapparatus of claim 4, wherein the fixing chuck comprises: a fixing blockmounted on the connection bracket; and a plurality of fixing pinsdisposed along an exterior circumference of the fixing block, andconfigured to be inserted into the fixing block and to protrude from thefixing block.
 6. The apparatus of claim 4, wherein the mold unitcomprises: a fixing plate coupled to the connection bracket through thefixing chuck; a support bar fixed to the fixing plate; and at least onemolding jig coupled with the at least one clamper and configured to bedriven by the at least one clamper to move along the support bar to moldthe head portion of the hairpin.
 7. The apparatus of claim 6, wherein:the at least one molding jig comprises a first jig and a second jigcoupled with the at least one clamper; and the first jig and the secondjig are configured to move to be closer or farther along a guide bar. 8.A method of inserting a hairpin into a stator core, the comprising:unwinding a coil spiral-wound on an uncoiler; forming a decoated portionby decoating a predetermined portion on the coil; bending the coil inmultiple stages to two-dimensionally form a leg portion and a headportion; cutting the coil formed with the leg portion and the headportion by a predetermined length; and moving the hairpin to be insertedinto the stator core while three-dimensionally forming the head portion.9. The method of claim 8, wherein bending the coil in multiple stages isperformed by a computerized numerical control bending device.
 10. Themethod of claim 8, wherein bending the coil in multiple stages isperformed by a press bending device.
 11. The method of claim 8, whereinmoving the hairpin to be inserted into the stator core whilethree-dimensionally forming the head portion comprises: coupling afixing block to a fixing chuck of a connection bracket while a moldingjig is inserted into at least one clamper; loading the coil such thatthe head portion that has been two-dimensionally formed is interposedbetween the molding jigs; three-dimensionally forming the head portionwhile the molding jigs are brought tightly close together by the atleast one clamper; and moving the hairpin while three-dimensionallyforming the head portion.
 12. The method of claim 11, wherein moving thehairpin to be inserted into the stator core while three-dimensionallyforming the head portion further comprises: aligning the hairpin into adummy core while forming the hairpin; and inserting a plurality ofhairpins aligned in the dummy core into slots of the stator core usingan extracting gripper unit.
 13. The method of claim 8, wherein formingthe decoated portion comprises using a heating device to heat the coiland peel off an insulating film of an enamel material.
 14. An apparatusfor molding a hairpin inserted into a stator core, the apparatuscomprising: a clamping unit including a connection bracket mounted on afront end of a robot arm and a pair of clampers mounted on theconnection bracket and configured to be reciprocally driven in oppositedirections in a straight line, wherein each clamper of the pair ofclampers comprises a first end mounted on the connection bracket and asecond end on which a fitting end protrudes; and a mold unit detachablycoupled with the connection bracket at a position between the pair ofclampers by a fixing chuck, detachably coupled with the pair ofclampers, and configured to press mold a head portion of the hairpin bya pair of molding jigs configured to be driven by the pair of clampers.15. The apparatus of claim 14, wherein the pair of clampers isconfigured to reciprocate to become closer and farther with reference toa central portion of the connection bracket.
 16. The apparatus of claim14, wherein: each molding jig of the pair of molding jigs comprises amounting slot; and the fitting ends of the pair of clampers are slidablyinserted into the mounting slots.
 17. The apparatus of claim 14, whereinthe fixing chuck comprises: a fixing block mounted on the connectionbracket; and a plurality of fixing pins disposed along an exteriorcircumference of the fixing block, and configured to be inserted intothe fixing block and to protrude from the fixing block.
 18. Theapparatus of claim 14, wherein the mold unit comprises: a fixing platecoupled to the connection bracket through the fixing chuck; and asupport bar fixed to the fixing plate, wherein the pair of molding jigsis configured to be driven by the pair of clampers to move along thesupport bar to mold the head portion of the hairpin.